class A {
    double f(double x, double y) {
        return x + y;
    }
}

class B extends A {
    double f(int x, int y) {
        return x * y;
    }
}

public class E {
    public static void main(String args[]) {
        // B b=new B();
        // System.out.println(b.f(3,5)); //【代码1】
        // System.out.println(b.f(3.0,5.0)); //【代码2】
        System.out.println("你好".matches("\\W\\W"));
	System.out.println(new String("abc") == new String("abc"));	
	String ss="\nello";
	System.out.println(ss);
	System.out.println("RedBird".indexOf("Bird"));
	String strOne="bird";
	String strTwo=strOne;
	strOne="flg";
	System.out.println(strTwo);
	byte[] d="abc我们喜欢篮球".getBytes();
	
	System.out.println(d[0]);
    }
}
